1. Field of the Invention
The present invention relates to technical fields of a transport stream multiplexing method for multiplexing encoded data and forming a transport stream, a transport stream multiplexing apparatus, and a storage and reproduction system for conducting storage and reproduction of a transport stream thus multiplexed.
2. Description of Related Art
In recent years, digital broadcasting in which video data and audio data are digitized and multiplex-transmitted is spreading. In such digital broadcasting, the MPEG (Moving Picture Expert Group) system is adopted as a compression coding system. In digital broadcasting using the MPEG system, data of a plurality of programs are multiplexed into an MPEG transport stream (hereafter referred to as MPEG-TS) and the MPEG transport stream is transmitted. Upon receiving this, the reception system side selectively extracts desired data. Furthermore, if a storage and reproduction system is formed so as to store arbitrary data contained in MPEG-TS by using a large capacity storage device such as a hard disk, it becomes possible to reproduce stored data at timing desired by the user.
By the way, in the case where video data stored in a storage device is reproduced in the aforementioned storage and reproduction system, it is desirable to provide a special reproduction processing function corresponding to fast feed and rewinding. In this case, it is necessary to selectively reproduce a sequence of access units (access units of video data) which becomes a subject of special reproduction, among the stored video data.
According to the aforementioned conventional storage and reproduction system, time information originally given to the selected access units becomes discontinuous. If an MPEG decoding device is made to conduct ordinary decoding processing by using such time information, contradiction occurs on the time axis. For a stream comprised of the aforementioned access units, therefore, it is necessary to set a different time axis and newly provide time information.
As the approach, such a configuration can be considered that elementary stream (ES) constituted by only an access unit to be reproduced specially is extracted from the TS packet sequence of video data at a time of special reproduction and decoding processing is performed using this ES. However, in such an approach, it is necessary to provide a decoder for decoding the ES in a dedicated manner, which results in lack in versatility of MPEG system.
As a technique therefor, it is conceivable to rewrite field portions of originally given time information with such time information as to be suitable for special reproduction while maintaining the form of the original stream of the video data at the time of special reproduction. However, since such a technique is processing of simply rewriting the original time information with new time information, it becomes necessary to locate the position of the field portion to be rewritten. In this case, it becomes necessary to, for example, eliminate dispersion of time required to locate the position. Thus, time management when determining the new time information becomes very complicated. Difficulty in ensuring the accuracy on the time axis poses a problem.